Thiol-benzoxazine chemistry as a novel Thiol-X reaction for the synthesis of block copolymers

•A new thiol-X coupling reaction based on the ring opening of benzoxazine molecules with thiols is demonstrated.•Its applicability on block copolymer formation of PS with PMA or PEG is shown.•The ease of benzoxazine synthesis and its design flexibility also are additional advantages in targeting polymers in such way.

A novel synthetic procedure is reported for the preparation of block copolymers by means of successive 1,3-benzoxazine-thiol and Husigen type azide-alkyne coupling methodologies in one-pot and sequential synthesis. The applied 1,3-benzoxazine-thiol process based on catalytic opening of the lateral benzoxazine rings by thiols is proposed as a new thiol-X chemistry. Azide functional poly(methyl acrylate) (PMA-N3), poly(ethylene glycol) (PEG-N3) and thiol functional polystyrene (PS-SH) were prepared. The obtained PMA-N3 or PEG-N3, PS-SH and propargyl benzoxazine as a click-linker were reacted in sequential or one-pot two step manner to yield desired PS-b-PMA and PS-b-PEG block copolymer. The described thiol-benzoxazine chemistry offers a facile and efficient route to exploring the many possibilities in macromolecular synthesis.

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